Graphene is a two-dimensional carbon allotrope, the electronic, optical, and magnetic properties of which can be tuned by engineering two-dimensional graphene sheets into one-dimensional structures with confined widths, known as graphene nanoribbons. The properties of graphene nanoribbons are highly dependent on their width and edge structure.
It has been proposed that graphene nanoribbons will outperform conventional materials and lead to next-generation technologies. Graphene nanoribbons have already shown tremendous promise for providing enhanced performance in nanoelectronics, spintronics, optoelectronics, plasmonic waveguiding, photodetection, solar energy conversion, molecular sensing, and catalysis. However, the full potential of graphene nanoribbons in such applications has not been realized.
A major challenge facing graphene nanoribbon-based devices is that scalable approaches to create high-quality graphene nanoribbons with atomically-smooth edges are lacking. Conventional, top-down techniques in which graphene nanoribbons are etched from continuous graphene sheets result in structures with rough, disordered edges that are riddled with defects, which significantly degrade graphene's exceptional properties. This blunt top-down etching can be avoided by synthesizing nanoribbons from the bottom-up. For instance, organic synthesis can yield ribbons with smooth edges, defined widths, and complex architectures. However, organic synthesis forms short nanoribbons (typically ˜20 nm in length) and is not adapted to technologically relevant substrates, such as insulators or semiconductors, limiting its potential for commercial development.